'Rockstar scientist' keeps digging for earthquake clues

Dr Mark Quigley. Photo / Greg Bowker

More than two years after the earthquake thrust him into the spotlight, Christchurch's Dr Mark Quigley is still hunting for clues that could unlock the seismic secrets hidden beneath the city.

Since Canterbury's September 4, 2010 quake and the devastating aftershock that killed 185 people on this day two years ago, the Canadian-born, skateboarding University of Canterbury geologist has given dozens of lectures, published major papers, picked up a slew of awards and received tens of thousands of hits on his website.

Dr Quigley is also staying staunch by his city, vowing to remain its calm voice for residents wanting to hear the latest post-quake research.

"There's an immense amount of science going into the rebuild, and my job as a geologist is to focus on what are viewed to be the key problems in that space, and do the best to put the best data forward."

He is exploring the history of the recently-discovered Greendale fault, the local causes of liquefaction and the occurrence of rock falls in the Port Hills.

Trenches are being dug across the Greendale fault to help scientists understand its history of rupturing.

"What we are finding is gravel channels that are 20,000 years old but have only been offset once, so some of those early assertions that this fault hasn't ruptured seem to be right."

Research around liquefaction, which would eventually be calibrated against geological data, would give a deeper perspective on how frequently the phenomenon occurred. And a project would use cosmogenic helium dating to determine what major rockfalls had taken place on the Port Hills.

"The process is like looking at your suntan to work out how long you've been in the sun - we look at the chemistry and skin of rocks to work out how long they've been sitting in position."

Early data indicated there had been a major rockfall event in the hills 3000 to 4000 years ago.

All would help form a slowly-evolving picture of Canterbury's earthquake profile, but much still remained unknown to scientists.

Dr Quigley, who has moved from his old ruined suburb of Bexley to Riccarton, said people were still keen to learn more about the processes happening beneath them.

When aftershocks hit, he usually saw a spike in views to his website.

"At the time of the crisis, people wanted to know why we got the quake, what the surface rupture looked like, why was there liquefaction and what it meant for us.

"But now the story has evolved, where people have said, okay, you've told us about the surface rupture, what do we do about that now?

"And of course, the answer is understanding how earthquakes deform the surface, it gives us an idea about how far we need to set critical infrastructure back from those faults we've identified.

"It gives us an idea about how these sorts of faults behave over time, so in other settings around New Zealand we can learn more about those sorts of faults."

Dr Quigley's sell-out lecture at Christchurch's 2400-seat town hall earned him the title of rockstar scientist but he found the exposure humbling.

And while he felt an obligation to inform the people of Christchurch, he felt the same strong bond that all other hard-hit residents did. "In the end, we like living here - that's the thing."